Sim's newest paintings start with ideas explored by 1970s hard-edge Op Art. His alternative to the pristine surfaces and clean solids of this tradition are modified and enhanced by the use of distressed and organically worked surfaces. Like his predecessors, he starts with a simple, geometric-shaped, linen canvas, and generates a dimensional illusion with line and color. Sims then avoids the temptation to seek perfection, instead introducing layers of striated color and texture that highlight a tension between the underlying geometry and the propensity towards decay of all physical objects.

The older paintings (pre-2015) process and distort symbols and images into near abstraction, retaining just enough of the image to retain a rudimentary recognition. He thoughtfully extends the reach of methods such as pixillation, halftoning, and patterning through manual means which humanizes the painting so that there is a warmth and handmade quality.

Sims' neon works are concerned with the interaction of light, space, and color.